There are many conventional traffic detection systems. Conventional systems typically utilize one or more sensor types, either in the roadway itself, or positioned at a roadside location or on traffic lights proximate to the roadway, to observe traffic patterns and detect specific objects. The most common type of sensors used are inductive coils, or loops, embedded in a road surface. Other existing systems utilize video cameras, radar sensors, acoustic sensors, or magnetometers, either in the road itself, or at either the side of a roadway or positioned higher above traffic to observe and detect vehicles and other objects in a desired area. Each of these sensors provide information used to determine a presence of vehicles and objects in specific lanes in intersections, and provide this information to traffic signal controllers for proper actuation.
This information is also useful for traffic and intersection management, in a variety of ways. For example, information from these sensors may be used for real-time decision-making pertaining to high speed approaches in enhanced “dilemma zone” precision, such as for example when a vehicle enters an area (known as the “dilemma zone”) in which the driver must decide whether to stop or proceed through an intersection with a changing signal.
When a traffic signal changes from green to yellow, drivers approaching the intersection will fall into 3 categories: 1) close enough to the stop line to safely traverse the intersection, 2) far enough back from the stop line to safely stop the vehicle, or 3) caught in a dilemma zone of whether to stop or proceed through the signal. It is well known in the transportation management industry that drivers can be caught in this dilemma zone. Depending on driver attitude, road conditions, and traffic conditions, the driver may stop the vehicle or accelerate through the intersection. Either situation may increase the risk of an accident.
Many existing systems and methods are available to traffic engineers for detecting when a vehicle may be in the dilemma zone, and they can choose a number of traffic control options to deal with this. They may, for example, hold a yellow phase cycle of the traffic signal to allow the vehicle to pass through the intersection before changing the next phase to green, and they may hold all phases in red to allow the vehicle to pass through the intersection before changing the next phase to green. Either of these solutions will reduce the risk of an accident. However, both of these solutions will negatively affect the efficient operation of the intersection and reduce overall traffic flow.
Phase timing at traffic signals occurs in cycles, and there are many methods of performing phase cycles at intersections. However, as traffic patterns change throughout the course of a day, interruptions to the timing for those phase cycles may occur for many different reasons. For example, simple roadway congestion, first responder/emergency vehicle interruptions, use of the intersection by slower moving users such as cyclists and pedestrians, and changes in dilemma zone behavior all affect timing of phase cycles, and there is no current approach for adjusting phase cycle timing at traffic intersections to account for these interruptions.
Accordingly, there is a need in the existing art for improvements in intersection traffic flow by adjusting phase cycle timing as traffic patterns change. There is also a need in the existing art for dynamically evaluating dilemma zone activity at a traffic intersection, and incorporating this information into traffic flow decision-making for making real-time adjustments to phase cycles of traffic signals.